DTC P0740 TCC Enable Solenoid Circuit Electrical Buick Built Before 6/17/96
Circuit Description
In conjunction with the Torque Converter Clutch Pulse Width Modulation Solenoid Valve (TCC PWM Sol. Valve), the Torque Converter Clutch Solenoid Valve (TCC Sol. Valve) controls the fluid acting on the TCC converter clutch valve. This controls the TCC apply and release. The PCM monitors the throttle position, the vehicle speed and other inputs in order to determine when to energize the TCC Sol. Valve. Circuit 241 supplies ignition voltage directly to the TCC Sol. Valve. The PCM controls the TCC Sol. Valve by providing the ground path through circuit 422. When you command the TCC Sol. Valve OFF, the PCM receives high voltage. When you command the TCC Sol. Valve ON, the PCM receives low voltage.
If the PCM detects low voltage when the TCC Sol. Valve is commanded OFF or high voltage when the TCC Sol. Valve is commanded ON, then DTC P0740 sets. DTC P0740 is a type A DTC.
Conditions for Setting the DTC
| • | The system voltage is 10-16 volts. |
| • | The engine speed is greater than 500 RPM for 5 seconds. |
| • | Not in fuel shut off |
| • | The PCM commands the solenoid ON and the voltage remains high (B+). |
| • | The PCM commands the solenoid OFF and the voltage remains low (0 volts). |
| • | All conditions must be met for 5 seconds. |
Action Taken When the DTC Sets
| • | The PCM inhibits TCC operation. |
| • | The PCM inhibits 4th gear, if the transmission is in hot mode. |
| • | The PCM illuminates the Malfunction Indicator Lamp (MIL). |
Conditions for Clearing the MIL/DTC
| • | The PCM turns OFF the MIL after three consecutive ignition cycles without a failure reported. |
| • | A scan tool can clear the DTC from the PCM history. The PCM clears the DTC from the PCM history if the vehicle completes 40 warm-up cycles without a failure reported. |
| • | The PCM cancels the DTC default actions when the fault no longer exists and the ignition is OFF long enough in order to power down the PCM. |
Diagnostic Aids
| • | Inspect the wiring for poor electrical connections at the PCM. Inspect the wiring at the transmission 7-way connector. Look for the following problems: |
| - | A bent terminal |
| - | A backed out terminal |
| - | A damaged terminal |
| - | Poor terminal tension |
| - | A chafed wire |
| - | A broken wire inside the insulation |
| • | When diagnosing for an intermittent short or open, massage the wiring harness while watching the test equipment for a change. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This Step isolates the fault between the engine harness and the transmission harness.
-
This Step verifies that circuit 422 is not open or shorted to power.
-
This Step verifies that the TCC Sol. Valve is not shorted across its windings or increased its resistance.
Step | Action | Value(s) | Yes | No | ||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | ||||||||||||||||||
2 |
Important: Before clearing the DTCs, use the scan tool in order to record the Freeze Frame and Failure Records for reference. Using the Clear Info function will erase the stored Freeze Frame and Failure Records from the PCM. Are DTCs P0753, P0758, and P1860 set? | -- | ||||||||||||||||||
3 | Remove the CLGFN/TCC fuse. Inspect the fuse for an open. Refer to Troubleshooting Procedures, Section 8. Did you find and correct a problem? | -- | ||||||||||||||||||
4 | Repair the short to ground in circuit 241. Refer to Troubleshooting Procedures, Section 8. Did you find and correct a problem? | -- | -- | |||||||||||||||||
5 | Repair the open in circuit 241. Refer to Troubleshooting Procedures, Section 8. Did you find and correct a problem? | -- | -- | |||||||||||||||||
Important: Additional DTCs will set. Is the test lamp ON? | -- | |||||||||||||||||||
7 | Inspect circuit 422 for a short to ground. Refer to Troubleshooting Procedures, Section 8. Did you find and correct a problem? | -- | ||||||||||||||||||
Does the test lamp cycle ON and OFF as commanded? | -- | |||||||||||||||||||
9 | Inspect circuit 422 for an open. Refer to Troubleshooting Procedures, Section 8. Did you find and correct a problem? | -- | ||||||||||||||||||
10 | Is the test lamp always OFF? | -- | -- | |||||||||||||||||
11 | Inspect circuit 422 for a short to power. Refer to Troubleshooting Procedures, Section 8. Did you find and correct a problem? | -- | ||||||||||||||||||
Is the measured resistance within the specified range? | 19-24ohms at 20°C (68°F) 24-31ohms at 88°C (190°F) | |||||||||||||||||||
13 | Is the resistance greater than the specified value? | 100ohms | ||||||||||||||||||
14 |
Refer to Troubleshooting Procedures, Section 8. Did you find and correct a problem? | -- | ||||||||||||||||||
15 | Connect the ohmmeter from terminal D of the jumper to ground. Is the measured resistance less than the specified value? | 100ohms | ||||||||||||||||||
16 | Inspect the TAN wire circuit 422 for a short to ground. Refer to Troubleshooting Procedures, Section 8. Was the problem found and corrected? | -- | -- | |||||||||||||||||
17 | Replace the TCC Sol. Valve. Refer to Solenoids and Wiring Harness, in On-Vehicle Service. Is the replacement complete? | -- | -- | |||||||||||||||||
18 | Replace the PCM. Refer to Powertrain Control Module Replacement/Programming , Section 6. Is the replacement complete? | -- | -- | |||||||||||||||||
19 | In order to verify your repair, perform the following procedure:
Has the test run and passed? | -- | System OK |
DTC P0740 TCC Enable Solenoid Circuit Electrical All Other Applications
Circuit Description
In conjunction with the Torque Converter Clutch Pulse Width Modulation Solenoid Valve (TCC PWM Sol. Valve), the Torque Converter Clutch Solenoid Valve (TCC Sol. Valve) controls the fluid acting on the TCC converter clutch valve. This controls the TCC apply and release. The PCM monitors the throttle position, the vehicle speed and other inputs in order to determine when to energize the TCC Sol. Valve. Circuit 639 supplies ignition voltage directly to the TCC Sol. Valve. The PCM controls the TCC Sol. Valve by providing the ground path through circuit 422. When you command the TCC Sol. Valve OFF, the PCM receives high voltage. When you command the TCC Sol. Valve ON, the PCM receives low voltage.
If the PCM detects low voltage when the TCC Sol. Valve is commanded OFF or high voltage when the TCC Sol. Valve is commanded ON, then DTC P0740 sets. DTC P0740 is a type A DTC.
Conditions for Setting the DTC
| • | The system voltage is 10-16 volts. |
| • | The engine speed is greater than 500 RPM for 5 seconds. |
| • | Not in fuel shut off |
| • | The PCM commands the solenoid ON and the voltage remains high (B+). |
| • | The PCM commands the solenoid OFF and the voltage remains low (0 volts). |
| • | All conditions must be met for 5 seconds. |
Action Taken When the DTC Sets
| • | The PCM inhibits TCC operation. |
| • | The PCM inhibits 4th gear, if the transmission is in hot mode. |
| • | The PCM illuminates the Malfunction Indicator Lamp (MIL). |
Conditions for Clearing the MIL/DTC
| • | The PCM turns OFF the MIL after three consecutive ignition cycles without a failure reported. |
| • | A scan tool can clear the DTC from the PCM history. The PCM clears the DTC from the PCM history if the vehicle completes 40 warm-up cycles without a failure reported. |
| • | The PCM cancels the DTC default actions when the fault no longer exists and the ignition is OFF long enough in order to power down the PCM. |
Diagnostic Aids
| • | Inspect the wiring for poor electrical connections at the PCM. Inspect the wiring at the transmission 7-way connector. Look for the following problems: |
| - | A bent terminal |
| - | A backed out terminal |
| - | A damaged terminal |
| - | Poor terminal tension |
| - | A chafed wire |
| - | A broken wire inside the insulation |
| • | When diagnosing for an intermittent short or open, massage the wiring harness while watching the test equipment for a change. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This Step isolates the fault between the engine harness and the transmission harness.
-
This Step verifies that circuit 422 is not open or shorted to power.
-
This Step verifies that the TCC Sol. Valve is not shorted across its windings or increased its resistance.
Step | Action | Value(s) | Yes | No | ||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | ||||||||||||||||||
2 |
Important: Before clearing the DTCs, use the scan tool in order to record the Freeze Frame and Failure Records for reference. Using the Clear Info function will erase the stored Freeze Frame and Failure Records from the PCM. Are DTCs P0753, P0758, and P1860 set? | -- | ||||||||||||||||||
3 | Remove the MISC ENG fuse. Inspect the fuse for an open. Refer to Troubleshooting Procedures, Section 8. Did you find and correct a problem? | -- | ||||||||||||||||||
4 | Repair the short to ground in circuit 639. Refer to Troubleshooting Procedures, Section 8. Did you find and correct a problem? | -- | -- | |||||||||||||||||
5 | Repair the open in circuit 639. Refer to Troubleshooting Procedures, Section 8. Did you find and correct a problem? | -- | -- | |||||||||||||||||
Important: Additional DTCs will set. Is the test lamp ON? | -- | |||||||||||||||||||
7 | Inspect circuit 422 for a short to ground. Refer to Troubleshooting Procedures, Section 8. Did you find and correct a problem? | -- | ||||||||||||||||||
Does the test lamp cycle ON and OFF as commanded? | -- | |||||||||||||||||||
9 | Inspect circuit 422 for an open. Refer to Troubleshooting Procedures, Section 8. Did you find and correct a problem? | -- | ||||||||||||||||||
10 | Is the test lamp always OFF? | -- | -- | |||||||||||||||||
11 | Inspect circuit 422 for a short to power. Refer to Troubleshooting Procedures, Section 8. Did you find and correct a problem? | -- | ||||||||||||||||||
Is the measured resistance within the specified range? | 19-24ohms at 20°C (68°F) 24-31ohms at 88°C (190°F) | |||||||||||||||||||
13 | Is the resistance greater than the specified value? | 100ohms | ||||||||||||||||||
14 |
Refer to Troubleshooting Procedures, Section 8. Did you find and correct a problem? | -- | ||||||||||||||||||
15 | Connect the ohmmeter from terminal D of the jumper to ground. Is the measured resistance less than the specified value? | 100ohms | ||||||||||||||||||
16 | Inspect the TAN wire circuit 422 for a short to ground. Refer to Troubleshooting Procedures, Section 8. Was the problem found and corrected? | -- | -- | |||||||||||||||||
17 | Replace the TCC Sol. Valve. Refer to Solenoids and Wiring Harness, in On-Vehicle Service. Is the replacement complete? | -- | -- | |||||||||||||||||
18 | Replace the PCM. Refer to Powertrain Control Module Replacement/Programming , Section 6. Is the replacement complete? | -- | -- | |||||||||||||||||
19 | In order to verify your repair, perform the following procedure:
Has the test run and passed? | -- | System OK |
